reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/thomas.weissschuh/linux.git/commit/?id=8cb2dc8e9b5a360dd41ca1df062e7a0045848c0b
        git remote add thomas-weissschuh https://git.kernel.org/pub/scm/linux/kernel/git/thomas.weissschuh/linux.git
        git fetch --no-tags thomas-weissschuh kunit-kselftests-integration
        git checkout 8cb2dc8e9b5a360dd41ca1df062e7a0045848c0b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash